narrator: he confirms that a large number of migrants haveome from the northern border region and from the metropolitan center, including mexico city. arth rio has, for almost a hundred years, beenheest central region, that is, jalisco, michoacan. and we found that indeed, it was stillhe most important gion for sendingignts. narrator: jones then sees a surprising cluster here, whheecit.jones:central mexi hascarcelyn udd byociascntists.we wererore suri narrator: jones then sees a surprising cluster here, hetumigratones:central mexi hom the nenand i a o is so, byociascntists.we wererore suri narrator: but to verify this,s ai needed to go into e field. narrator: nes's research has brought him here, to the mesa e, a high dry plateau beginning near mexico city and stretching to the u.s. border.